Scroll compressor with captured thrust washer

ABSTRACT

A load transmittal apparatus transfers an axial load to a thrust surface during operation of a scroll compressor.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation of co-pending U.S. patentapplication Ser. No. 13/428,165, filed Mar. 23, 2012, the entireteachings and disclosure of which are incorporated herein by referencethereto.

FIELD OF THE INVENTION

The present invention generally relates to scroll compressors forcompressing refrigerant and more particularly to a load transmittalapparatus for transferring an axial load to a thrust surface duringoperation of the scroll compressor.

BACKGROUND OF THE INVENTION

A scroll compressor is a certain type of compressor that is used tocompress refrigerant for such applications as refrigeration, airconditioning, industrial cooling and freezer applications, and/or otherapplications where compressed fluid may be used. Such prior scrollcompressors are known, for example, as exemplified in U.S. Pat. No.6,398,530 to Hasemann; U.S. Pat. No. 6,814,551, to Kammhoff et al.; U.S.Pat. No. 6,960,070 to Kammhoff et al.; and 7,112,046 to Kammhoff et al.,all of which are assigned to a Bitzer entity closely related to thepresent assignee. As the present disclosure pertains to improvementsthat can be implemented in these or other scroll compressor designs, theentire disclosures of U.S. Pat. Nos. 6,398,530; 7,112,046; 6,814,551;and 6,960,070 are hereby incorporated by reference in their entireties.

As is exemplified by these patents, scroll compressors assembliesconventionally include an outer housing having a scroll compressorcontained therein. A scroll compressor includes first and second scrollcompressor members. A first compressor member is typically arrangedstationary and fixed in the outer housing. A second scroll compressormember is movable relative to the first scroll compressor member inorder to compress refrigerant between respective scroll ribs which riseabove the respective bases and engage in one another. Conventionally themovable scroll compressor member is driven about an orbital path about acentral axis for the purposes of compressing refrigerant. An appropriatedrive unit, typically an electric motor, is provided usually within thesame housing to drive the movable scroll member.

In some scroll compressors, it is known to have axial restraint, wherebythe fixed scroll member has a limited range of movement. This can bedesirable due to thermal expansion when the temperature of the orbitingscroll and fixed scroll increases causing these components to expand.Examples of an apparatus to control such restraint are shown in U.S.Pat. No. 5,407,335, issued to Caillat et al., the entire disclosure ofwhich is hereby incorporated by reference.

In a scroll compressor, there is typically some amount of load that isinduced in the axial direction of the crankshaft. For a vertical scrollcompressor, this load is a combination of the mass of the rotatingcomponents as well as any electrically induced load caused byintentional or unintentional axial misalignment of the motor stator andmotor rotor. These loads are commonly transmitted between the rotatingcrankshaft and a stationary housing using a thrust surface. The thrustsurface may be designed into the stationary component but such surfacetends to wear away and surface preparation must be given carefulconsideration which adds costs to the compressor. It is also known touse a thrust washer, but to prevent unwanted movement, such thrustwasher is fixed in place with various ways including the use offastener(s), adhesive or tabs formed into the circumference of thewasher. Such methods add cost to the compressor.

The present disclosure is directed towards improvements over the stateof the art as it relates to the above-described features and otherfeatures of scroll compressors.

BRIEF SUMMARY OF THE INVENTION

There is provided a scroll compressor including a load transferapparatus. The scroll compressor includes a rotating shaft and astationary lower bearing member. The load transfer apparatus includes acentral cylindrical hub defined by the stationary lower bearing member,with the central hub further defining an opening. A cylindrical bearingis configured to seat in the opening. The cylindrical bearing isconfigured to receive one end of the rotating shaft of the scrollcompressor. A thrust washer is disposed in the opening of the centralhub and captured axially within the lower bearing member by thecylindrical bearing. An axial load along the center line of the shafttransmits to the stationary lower bearing member through the thrustwasher.

A load transfer apparatus of the present disclosure captures the thrustwasher in the opening without the use of a fastener or an adhesive. Thethrust washer is configured with a smooth circumference, meaning thereare no tabs or notches on the circumference of the thrust washer. In oneembodiment the thrust washer is metal and in another embodiment thethrust washer is composed of a matrix of a metal, for example steel,bronze, and aluminum, and a polymeric layer, for example PTFE, glassfibers, graphite fibers, silica, molybdenum disulfide or combinations ofsuch material. The cylindrical bearing can also be composed of a metal,and a matrix of metal and a polymeric layer as described above.

There is further provided a scroll compressor including a housing havingan upper end and a lower end. A pair of scroll compressor bodies aredisposed in the housing. The scroll bodies include a first scroll bodyand a second scroll body, with the first and second scroll bodies havingrespective bases and respective scroll ribs that project from therespective bases. The scroll ribs mutually engage each other with thesecond scroll body being moveable relative to the first scroll body fora compressing fluid.

A pilot ring engages a perimeter surface of the first scroll body tolimit movement of the first scroll body in the radial direction. Thefirst scroll body has a first radially-outward-projecting limit tabbeing configured to limit movement of the first scroll body and at leastone of the axial and rotational directions.

A stationary lower bearing member is disposed proximate the lower end ofthe housing. A motor is disposed in the housing, with the motorincluding a stator and a rotor with the rotor coupled to a shaftconfigured to rotate within the housing and with the pair of scrollcompressor bodies coupled to the shaft.

A load transfer apparatus includes a central cylindrical hub defined byits stationary lower bearing member with the central hub defining anopening. A cylindrical bearing is configured to seat in the opening,with the cylindrical bearing further configured to receive one end ofthe shaft. A thrust washer is disposed in the opening of the central huband captured axially within the lower bearing member by the cylindricalbearing. An axial load along the center line of the shaft is transmittedto the stationary lower bearing member through the thrust washer.

In another embodiment, the pilot ring is formed separately from acrankshaft case, with the pilot ring being attached to a crankcase via aplurality of posts extending axially therebetween. The first and secondscroll bodies are disposed within the attached pilot ring and crankcase.A key coupling that acts upon the second scroll body, is disposed withinthe attached pilot ring and crankcase. The key coupling extends intospaces between adjacent posts, and the spaces allow the pilot ring,crankcase, and key coupling to have outer diameters that areapproximately equal to the inner diameter of the housing.

In another aspect, embodiments of the scroll compressor provide a methodof transferring axial loading from a rotating shaft in the scrollcompressor to a stationary lower bearing member of the scrollcompressor. An axial load on the rotating shaft typically includes themass of the shaft, a motor rotor, and counter weights of the scrollcompressor plus electrical-induced loads caused by misalignment of themotor rotor and a motor stator. The method includes depositing a thrustwasher at the bottom of an opening in a central cylindrical hub definedby the stationary load bearing member. A cylindrical bearing is insertedinto the opening in the central cylindrical hub. The cylindrical bearingis pressed into the opening axially until the bearing captures thethrust washer into position axially in the opening. An end of the shaftis inserted into the cylindrical bearing in the opening defined in thecentral cylindrical hub, wherein the axial load on the shaft around thecenter line of the shaft is transmitted to the stationary load bearingmember through the thrust washer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a cross-sectional isometric view of a scroll compressorassembly, according to an embodiment of the invention;

FIG. 2 is a cross-sectional isometric view of an upper portion of thescroll compressor assembly of FIG. 1;

FIG. 3 is an exploded isometric view of selected components of thescroll compressor assembly of FIG. 1;

FIG. 4 is a perspective view of an exemplary key coupling and movablescroll compressor body, according to an embodiment of the invention;

FIG. 5 is a top isometric view of the pilot ring, constructed inaccordance with an embodiment of the invention;

FIG. 6 is a bottom isometric view of the pilot ring of FIG. 5;

FIG. 7 is an exploded isometric view of the pilot ring, crankcase, keycoupler and scroll compressor bodies, according to an embodiment of theinvention;

FIG. 8 is a isometric view of the components of FIG. 7 shown assembled;

FIG. 9 is a cross-sectional isometric view of the components in the topend section of the outer housing, according to an embodiment of theinvention;

FIG. 10 is an exploded isometric view of the components of FIG. 9;

FIG. 11 is a bottom isometric view of the floating seal, according to anembodiment of the invention;

FIG. 12 is a top isometric view of the floating seal of FIG. 11;

FIG. 13 is an exploded isometric view of selected components for analternate embodiment of the scroll compressor assembly; and

FIG. 14 is a cross-sectional isometric view of a portion of a scrollcompressor assembly, constructed in accordance with an embodiment of theinvention.

FIG. 15 is an exploded isometric view of components of the scrollcompressor of FIG. 1 including an exemplary embodiment of a loadtransfer apparatus.

FIG. 16 is a detail assembled cross-section view of the load transferapparatus illustrated in FIG. 15.

FIG. 17 is a detail exploded cross-section view of the load transferapparatus components illustrated in FIG. 15.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is illustrated in the figures asa scroll compressor assembly 10 generally including an outer housing 12in which a scroll compressor 14 can be driven by a drive unit 16. Thescroll compressor assembly 10 may be arranged in a refrigerant circuitfor refrigeration, industrial cooling, freezing, air conditioning orother appropriate applications where compressed fluid is desired.Appropriate connection ports provide for connection to a refrigerationcircuit and include a refrigerant inlet port 18 and a refrigerant outletport 20 extending through the outer housing 12. The scroll compressorassembly 10 is operable through operation of the drive unit 16 tooperate the scroll compressor 14 and thereby compress an appropriaterefrigerant or other fluid that enters the refrigerant inlet port 18 andexits the refrigerant outlet port 20 in a compressed high-pressurestate.

The outer housing for the scroll compressor assembly 10 may take manyforms. In particular embodiments of the invention, the outer housing 12includes multiple shell sections. In the embodiment of FIG. 1, the outerhousing 12 includes a central cylindrical housing section 24, and a topend housing section 26, and a single-piece bottom shell 28 that servesas a mounting base. In certain embodiments, the housing sections 24, 26,28 are formed of appropriate sheet steel and welded together to make apermanent outer housing 12 enclosure. However, if disassembly of thehousing is desired, other housing assembly provisions can be made thatcan include metal castings or machined components, wherein the housingsections 24, 26, 28 are attached using fasteners.

As can be seen in the embodiment of FIG. 1, the central housing section24 is cylindrical, joined with the top end housing section 26. In thisembodiment, a separator plate 30 is disposed in the top end housingsection 26. During assembly, these components can be assembled such thatwhen the top end housing section 26 is joined to the central cylindricalhousing section 24, a single weld around the circumference of the outerhousing 12 joins the top end housing section 26, the separator plate 30,and the central cylindrical housing section 24. In particularembodiments, the central cylindrical housing section 24 is welded to thesingle-piece bottom shell 28, though, as stated above, alternateembodiments would include other methods of joining (e.g., fasteners)these sections of the outer housing 12. Assembly of the outer housing 12results in the formation of an enclosed chamber 31 that surrounds thedrive unit 16, and partially surrounds the scroll compressor 14. Inparticular embodiments, the top end housing section 26 is generallydome-shaped and includes a respective cylindrical side wall region 32that abuts the top of the central cylindrical housing section 24, andprovides for closing off the top end of the outer housing 12. As canalso be seen from FIG. 1, the bottom of the central cylindrical housingsection 24 abuts a flat portion just to the outside of a raised annularrib 34 of the bottom end housing section 28. In at least one embodimentof the invention, the central cylindrical housing section 24 and bottomend housing section 28 are joined by an exterior weld around thecircumference of a bottom end of the outer housing 12.

In a particular embodiment, the drive unit 16 in is the form of anelectrical motor assembly 40. The electrical motor assembly 40 operablyrotates and drives a shaft 46. Further, the electrical motor assembly 40generally includes a stator 50 comprising electrical coils and a rotor52 that is coupled to the drive shaft 46 for rotation together. Thestator 50 is supported by the outer housing 12, either directly or viaan adapter. The stator 50 may be press-fit directly into outer housing12, or may be fitted with an adapter (not shown) and press-fit into theouter housing 12. In a particular embodiment, the rotor 52 is mounted onthe drive shaft 46, which is supported by upper and lower bearings 42,44. Energizing the stator 50 is operative to rotatably drive the rotor52 and thereby rotate the drive shaft 46 about a central axis 54.Applicant notes that when the terms “axial” and “radial” are used hereinto describe features of components or assemblies, they are defined withrespect to the central axis 54. Specifically, the term “axial” or“axially-extending” refers to a feature that projects or extends in adirection parallel to the central axis 54, while the terms “radial’ or“radially-extending” indicates a feature that projects or extends in adirection perpendicular to the central axis 54.

In one embodiment an axial load induced along the centerline 54 of thecrankshaft 46 is transferred to the stationary lower bearing member 44by a load transfer apparatus 65.

Referring to FIGS. 15-17, an exemplary embodiment of a load transferapparatus 65 is illustrated in an assembled view and an exploded view. Acentral cylindrical hub 58 is defined in the lower bearing member 44,with the cylindrical hub 58 further defining an opening 59. The openingis configured to receive one end 49 of the shaft 46 and a cylindricalbearing 60. The bearing 60 is lubricated by oil through an orifice 81defined in the shaft 46. The orifice 81 is in fluid communication withthe internal lubricant passageway 80 defined by the shaft 46.

A thrust washer 55 is disposed in the opening 59 at the bottom of thecentral cylindrical hub 58 (See FIG. 16). The thrust washer 55 isdisposed between the cylindrical bearing 60 and the stationary lowerbearing 44. In one configuration the thrust washer 55 is captured in theopening 59 by the cylindrical bearing 60. During compressor 14operation, since the friction between the shaft 46 and thrust washer 55is substantially less than the friction between the thrust washer 55 atthe bearing housing 44 the thrust washer 55 will remain stationary, i.e.will not spin with the shaft 46 or move axially. In anotherconfiguration the cylindrical bearing 60 is pressed into the opening 59axially until sufficient force is exerted against the thrust washer 55to capture the thrust washer in position axially but allow the thrustwasher 55 to rotate since there is some axial clearance between thecylindrical bearing and the washer. With the load transfer apparatus 65,there is no need to fix the thrust washer 55 in position with adhesive,fasteners or other means, for example tabs defined on the circumferenceof the thrust washer 55. The thrust washer 55 in the described loadtransfer apparatus 65 is configured with a smooth circumference, i.e. notabs, grooves or projections. The thrust washer 55 is composed of one ofa metal or a metal and a polymeric layer capable of transferring theaxial load from the shaft 46 to the lower bearing 44.

The two bearings, cylindrical 60 or thrust washer 55, can be either allmetal or a metal-nonmetal assemblage. In a typical configuration, eitheror both bearings are composed of three layers. The outermost (away fromthe load bearing surface) is steel (to provide structural strength. Tothis is bonded a layer of sintered bronze particles in a “loose” (i.e.porous) matrix. Finally a polymeric layer is bonded into the porousmatrix. The polymeric layer may also include PTFE, glass fibers orparticles, graphite fibers or particles, silica, molybdenum disulfide,and/or other fillers. Alternately, all-metal bearings will typicallyhave the steel shell and a solid bronze or babbitt liner. Some othersmay have a steel shell and porous bronze liner with a polymer or PTFEfiling the bronze matrix but not forming an actual layer on top of thebronze. Another configuration is a bearing made of a single metal,without the described layered construction. In this case the material istypically a bronze or aluminum alloy.

The axial load is typically the combination of the mass of the rotatingcomponents that include the shaft 46, the motor rotor 52 and counterweight and other members coupled to the shaft 46. The axial load alsoincludes any electrical induced load caused by intentional orunintentional axial misalignment of the motor stator 50 and motor rotor52.

With reference to FIG. 1, the lower bearing member 44 includes acentral, generally cylindrical hub 58 that includes a central bushing 58and opening 59 to provide the cylindrical bearing 60 to which the driveshaft 46 is journaled for rotational support. A plate-like ledge region68 of the lower bearing member 44 projects radially outward from thecentral hub 58, and serves to separate a lower portion of the stator 50from an oil lubricant sump 76. An axially-extending perimeter surface 70of the lower bearing member 44 may engage with the inner diametersurface of the central housing section 24 to centrally locate the lowerbearing member 44 and thereby maintain its position relative to thecentral axis 54. This can be by way of an interference and press-fitsupport arrangement between the lower bearing member 44 and the outerhousing 12.

In the embodiment of FIG. 1, the drive shaft 46 has an impeller tube 47attached at the bottom end of the drive shaft 46. In a particularembodiment, the impeller tube 47 is of a smaller diameter than the driveshaft 46, and is aligned concentrically with the central axis 54. As canbe seen from FIG. 1, the drive shaft 46 and impeller tube 47 passthrough an opening in the cylindrical hub 58 of the lower bearing member44. At its upper end, the drive shaft 46 is journaled for rotationwithin the upper bearing member 42. Upper bearing member 42 may also bereferred to as a “crankcase.”

The drive shaft 46 further includes an offset eccentric drive section 74that has a cylindrical drive surface 75 (shown in FIG. 2) about anoffset axis that is offset relative to the central axis 54. This offsetdrive section 74 is journaled within a cavity of a movable scrollcompressor body 112 of the scroll compressor 14 to drive the movablescroll compressor body 112 about an orbital path when the drive shaft 46rotates about the central axis 54. To provide for lubrication of all ofthe various bearing surfaces, the outer housing 12 provides the oillubricant sump 76 at the bottom end of the outer housing 12 in whichsuitable oil lubricant is provided. The impeller tube 47 has an oillubricant passage and inlet port 78 formed at the end of the impellertube 47. Together, the impeller tube 47 and inlet port 78 act as an oilpump when the drive shaft 46 is rotated, and thereby pumps oil out ofthe lubricant sump 76 into an internal lubricant passageway 80 definedwithin the drive shaft 46. During rotation of the drive shaft 46,centrifugal force acts to drive lubricant oil up through the lubricantpassageway 80 against the action of gravity. The lubricant passageway 80has various radial passages projecting therefrom to feed oil throughcentrifugal force to appropriate bearing surfaces and thereby lubricatesliding surfaces as may be desired.

As shown in FIGS. 2 and 3, the upper bearing member, or crankcase, 42includes a central bearing hub 87 into which the drive shaft 46 isjournaled for rotation, and a thrust bearing 84 that supports themovable scroll compressor body 112. (See also FIG. 9). Extending outwardfrom the central bearing hub 87 is a disk-like portion 86 thatterminates in an intermittent perimeter support surface 88 defined bydiscretely spaced posts 89. In the embodiment of FIG. 3, the centralbearing hub 87 extends below the disk-like portion 86, while the thrustbearing 84 extends above the disk-like portion 86. In certainembodiments, the intermittent perimeter support surface 88 is adapted tohave an interference and press-fit with the outer housing 12. In theembodiment of FIG. 3, the crankcase 42 includes four posts 89, each posthaving an opening 91 configured to receive a threaded fastener. It isunderstood that alternate embodiments of the invention may include acrankcase with more or less than four posts, or the posts may beseparate components altogether. Alternate embodiments of the inventionalso include those in which the posts are integral with the pilot ringinstead of the crankcase.

In certain embodiments such as the one shown in FIG. 3, each post 89 hasan arcuate outer surface 93 spaced radially inward from the innersurface of the outer housing 12, angled interior surfaces 95, and agenerally flat top surface 97 which can support a pilot ring 160. Inthis embodiment, intermittent perimeter support surface 88 abuts theinner surface of the outer housing 12. Further, each post 89 has achamfered edge 94 on a top, outer portion of the post 89. In particularembodiments, the crankcase 42 includes a plurality of spaces 244 betweenadjacent posts 89. In the embodiment shown, these spaces 244 aregenerally concave and the portion of the crankcase 42 bounded by thesespaces 244 will not contact the inner surface of the outer housing 12.

The upper bearing member or crankcase 42 also provides axial thrustsupport to the movable scroll compressor body 112 through a bearingsupport via an axial thrust surface 96 of the thrust bearing 84. While,as shown FIGS. 1-3, the crankcase 42 may be integrally provided by asingle unitary component, FIGS. 13 and 14 show an alternate embodimentin which the axial thrust support is provided by a separate collarmember 198 that is assembled and concentrically located within the upperportion of the upper bearing member 199 along stepped annular interface100. The collar member 198 defines a central opening 102 that is a sizelarge enough to clear a cylindrical bushing drive hub 128 of the movablescroll compressor body 112 in addition to the eccentric offset drivesection 74, and allow for orbital eccentric movement thereof.

Turning in greater detail to the scroll compressor 14, the scrollcompressor includes first and second scroll compressor bodies whichpreferably include a stationary fixed scroll compressor body 110 and amovable scroll compressor body 112. While the term “fixed” generallymeans stationary or immovable in the context of this application, morespecifically “fixed” refers to the non-orbiting, non-driven scrollmember, as it is acknowledged that some limited range of axial, radial,and rotational movement is possible due to thermal expansion and/ordesign tolerances.

The movable scroll compressor body 112 is arranged for orbital movementrelative to the fixed scroll compressor body 110 for the purpose ofcompressing refrigerant. The fixed scroll compressor body includes afirst rib 114 projecting axially from a plate-like base 116 and isdesigned in the form of a spiral. Similarly, the movable scrollcompressor body 112 includes a second scroll rib 118 projecting axiallyfrom a plate-like base 120 and is in the shape of a similar spiral. Thescroll ribs 114, 118 engage in one another and abut sealingly on therespective surfaces of bases 120, 116 of the respectively othercompressor body 112, 110. As a result, multiple compression chambers 122are formed between the scroll ribs 114, 118 and the bases 120, 116 ofthe compressor bodies 112, 110. Within the chambers 122, progressivecompression of refrigerant takes place. Refrigerant flows with aninitial low pressure via an intake area 124 surrounding the scroll ribs114, 118 in the outer radial region (see e.g. FIGS. 1-2). Following theprogressive compression in the chambers 122 (as the chambersprogressively are defined radially inward), the refrigerant exits via acompression outlet 126 which is defined centrally within the base 116 ofthe fixed scroll compressor body 110. Refrigerant that has beencompressed to a high pressure can exit the chambers 122 via thecompression outlet 126 during operation of the scroll compressor 14.

The movable scroll compressor body 112 engages the eccentric offsetdrive section 74 of the drive shaft 46. More specifically, the receivingportion of the movable scroll compressor body 112 includes thecylindrical bushing drive hub 128 which slideably receives the eccentricoffset drive section 74 with a slideable bearing surface providedtherein. In detail, the eccentric offset drive section 74 engages thecylindrical bushing drive hub 128 in order to move the movable scrollcompressor body 112 about an orbital path about the central axis 54during rotation of the drive shaft 46 about the central axis 54.Considering that this offset relationship causes a weight imbalancerelative to the central axis 54, the assembly typically includes acounterweight 130 that is mounted at a fixed angular orientation to thedrive shaft 46. The counterweight 130 acts to offset the weightimbalance caused by the eccentric offset drive section 74 and themovable scroll compressor body 112 that is driven about an orbital path.The counterweight 130 includes an attachment collar 132 and an offsetweight region 134 (see counterweight 130 shown best in FIGS. 2 and 3)that provides for the counterweight effect and thereby balancing of theoverall weight of the components rotating about the central axis 54.This provides for reduced vibration and noise of the overall assembly byinternally balancing or cancelling out inertial forces.

With reference to FIGS. 4 and 7, the guiding movement of the scrollcompressor 14 can be seen. To guide the orbital movement of the movablescroll compressor body 112 relative to the fixed scroll compressor body110, an appropriate key coupling 140 may be provided. Keyed couplings140 are often referred to in the scroll compressor art as an “OldhamCoupling.” In this embodiment, the key coupling 140 includes an outerring body 142 and includes two axially-projecting first keys 144 thatare linearly spaced along a first lateral axis 146 and that slideclosely and linearly within two respective keyway tracks or slots 115(shown in FIGS. 1 and 2) of the fixed scroll compressor body 110 thatare linearly spaced and aligned along the first axis 146 as well. Theslots 115 are defined by the stationary fixed scroll compressor body 110such that the linear movement of the key coupling 140 along the firstlateral axis 146 is a linear movement relative to the outer housing 12and perpendicular to the central axis 54. The keys can comprise slots,grooves or, as shown, projections which project axially (i.e., parallelto central axis 54) from the ring body 142 of the key coupling 140. Thiscontrol of movement along the first lateral axis 146 guides part of theoverall orbital path of the movable scroll compressor body 112.

Referring specifically to FIG. 4, the key coupling 140 includes fouraxially-projecting second keys 152 in which opposed pairs of the secondkeys 152 are linearly aligned substantially parallel relative to asecond transverse lateral axis 154 that is perpendicular to the firstlateral axis 146. There are two sets of the second keys 152 that actcooperatively to receive projecting sliding guide portions 254 thatproject from the base 120 on opposite sides of the movable scrollcompressor body 112. The guide portions 254 linearly engage and areguided for linear movement along the second transverse lateral axis byvirtue of sliding linear guiding movement of the guide portions 254along sets of the second keys 152.

It can be seen in FIG. 4 that four sliding contact surfaces 258 areprovided on the four axially-projecting second keys 152 of the keycoupling 140. As shown, each of the sliding contact surfaces 258 iscontained in its own separate quadrant 252 (the quadrants 252 beingdefined by the mutually perpendicular lateral axes 146, 154). As shown,cooperating pairs of the sliding contact surfaces 258 are provided oneach side of the first lateral axis 146.

By virtue of the key coupling 140, the movable scroll compressor body112 has movement restrained relative to the fixed scroll compressor body110 along the first lateral axis 146 and second transverse lateral axis154. This results in the prevention of relative rotation of the movablescroll body as it allows only translational motion. More particularly,the fixed scroll compressor body 110 limits motion of the key coupling140 to linear movement along the first lateral axis 146; and in turn,the key coupling 140 when moving along the first lateral axis 146carries the movable scroll 112 along the first lateral axis 146therewith. Additionally, the movable scroll compressor body canindependently move relative to the key coupling 140 along the secondtransverse lateral axis 154 by virtue of relative sliding movementafforded by the guide portions 254 which are received and slide betweenthe second keys 152. By allowing for simultaneous movement in twomutually perpendicular axes 146, 154, the eccentric motion that isafforded by the eccentric offset drive section 74 of the drive shaft 46upon the cylindrical bushing drive hub 128 of the movable scrollcompressor body 112 is translated into an orbital path movement of themovable scroll compressor body 112 relative to the fixed scrollcompressor body 110.

To carry axial thrust loads, the movable scroll compressor body 112 alsoincludes flange portions 268 projecting in a direction perpendicularrelative to the guiding flange portions 262 (e.g. along the firstlateral axis 146). These additional flange portions 268 are preferablycontained within the diametrical boundary created by the guide flangeportions 262 so as to best realize the size reduction benefits. Yet afurther advantage of this design is that the sliding faces 254 of themovable scroll compressor body 112 are open and not contained within aslot. This is advantageous during manufacture in that it affordssubsequent machining operations such as finishing milling for creatingthe desirable tolerances and running clearances as may be desired.

Generally, scroll compressors with movable and fixed scroll compressorbodies require some type of restraint for the fixed scroll compressorbody 110 which restricts the radial movement and rotational movement butwhich allows some degree of axial movement so that the fixed and movablescroll compressor bodies 110, 112 are not damaged during operation ofthe scroll compressor 14. In embodiments of the invention, thatrestraint is provided by a pilot ring 160, as shown in FIGS. 5-9. FIG. 5shows the top side of pilot ring 160, constructed in accordance with anembodiment of the invention. The pilot ring 160 has a top surface 167, acylindrical outer perimeter surface 178, and a cylindrical first innerwall 169. The pilot ring 160 of FIG. 5 includes four holes 161 throughwhich fasteners, such as threaded bolts, may be inserted to allow forattachment of the pilot ring 160 to the crankcase 42. In a particularembodiment, the pilot ring 160 has axially-raised portions 171 (alsoreferred to as mounting bosses) where the holes 161 are located. One ofskill in the art will recognize that alternate embodiments of the pilotring may have greater or fewer than four holes for fasteners. The pilotring 160 may be a machined metal casting, or, in alternate embodiments,a machined component of iron, steel, aluminum, or some other similarlysuitable material.

FIG. 6 shows a bottom view of the pilot ring 160 showing the four holes161 along with two slots 162 formed into the pilot ring 160. In theembodiment of FIG. 6, the slots 162 are spaced approximately 180 degreesapart on the pilot ring 160. Each slot 162 is bounded on two sides byaxially-extending side walls 193. As shown in FIG. 6, the bottom side ofthe pilot ring 160 includes a base portion 163 which is continuousaround the entire circumference of the pilot ring 160 forming a completecylinder. But on each side of the two slots 162, there is asemi-circular stepped portion 164 which covers some of the base portion163 such that a ledge 165 is formed on the part of the pilot ring 160radially inward of each semi-circular stepped portion 164. Theinner-most diameter or the ledge 165 is bounded by the first inner wall169.

A second inner wall 189 runs along the inner diameter of eachsemi-circular stepped portion 164. Each semi-circular stepped portion164 further includes a bottom surface 191, a notched section 166, and achamfered lip 190. In the embodiment of FIG. 6, each chamfered lip 190runs the entire length of the semi-circular stepped portion 164 makingthe chamfered lip 190 semi-circular as well. Each chamfered lip 190 islocated on the radially-outermost edge of the bottom surface 191, andextends axially from the bottom surface 191. Further, each chamfered lip190 includes a chamfered edge surface 192 on an inner radius of thechamfered lip 190. When assembled, the chamfered edge surface 192 isconfigured to mate with the chamfered edge 94 on each post 89 of thecrankcase. The mating of these chamfered surfaces allows for an easier,better-fitting assembly, and reduces the likelihood of assembly problemsdue to manufacturing tolerances.

In the embodiment of FIG. 6, the notched sections 166 are approximately180 degrees apart on the pilot ring 160, and each is about midwaybetween the two ends of the semi-circular stepped portion 164. Thenotched sections 166 are bounded on the sides by sidewall sections 197.Notched sections 166 thus extend radially and axially into thesemi-circular stepped portion 164 of the pilot ring 160.

FIG. 7 shows an exploded view of the scroll compressor 14 assembly,according to an embodiment of the invention. The top-most componentshown is the pilot ring 160 which is adapted to fit over the top of thefixed scroll compressor body 110. The fixed scroll compressor body 110has a pair of first radially-outward projecting limit tabs 111. In theembodiment of FIG. 7, one of the pair of first radially-outwardprojecting limit tabs 111 is attached to an outermost perimeter surface117 of the first scroll rib 114, while the other of the pair of firstradially-outward projecting limit tabs 111 is attached to a perimeterportion of the fixed scroll compressor body 110 below a perimetersurface 119. In further embodiments, the pair of first radially-outwardprojecting limit tabs 111 are spaced approximately 180 degrees apart.Additionally, in particular embodiments, each of the pair of firstradially-outward-projecting limit tabs 111 has a slot 115 therein. Inparticular embodiments, the slot 115 may be a U-shaped opening, arectangular-shaped opening, or have some other suitable shape.

The fixed scroll compressor body 110 also has a pair of secondradially-outward projecting limit tabs 113, which, in this embodiment,are spaced approximately 180 degrees apart. In certain embodiments, thesecond radially-outward projecting limit tabs 113 share a common planewith the first radially-outward-projecting limit tabs 111. Additionally,in the embodiment of FIG. 7, one of the pair of second radially-outwardprojecting limit tabs 113 is attached to an outermost perimeter surface117 of the first scroll rib 114, while the other of the pair of secondradially-outward projecting limit tabs 113 is attached to a perimeterportion of the fixed scroll compressor body 110 below the perimetersurface 119. The movable scroll compressor body 112 is configured to beheld within the keys of the key coupling 140 and mates with the fixedscroll compressor body 110. As explained above, the key coupling 140 hastwo axially-projecting first keys 144, which are configured to bereceived within the slots 115 in the first radially-outward-projectinglimit tabs 111. When assembled, the key coupling 140, fixed and movablescroll compressor bodies 110, 112 are all configured to be disposedwithin crankcase 42, which can be attached the to the pilot ring 160 bythe threaded bolts 168 shown above the pilot ring 160.

Referring still to FIG. 7, the fixed scroll compressor body 110 includesplate-like base 116 (see FIG. 14) and a perimeter surface 119 spacedaxially from the plate-like base 116. In a particular embodiment, theentirety of the perimeter surface 119 surrounds the first scroll rib 114of the fixed scroll compressor body 110, and is configured to abut thefirst inner wall 169 of the pilot ring 160, though embodiments arecontemplated in which the engagement of the pilot ring and fixed scrollcompressor body involve less than the entire circumference. Inparticular embodiments of the invention, the first inner wall 169 isprecisely toleranced to fit snugly around the perimeter surface 119 tothereby limit radial movement of the first scroll compressor body 110,and thus provide radial restraint for the first scroll compressor body110. The plate-like base 116 further includes a radially-extending topsurface 121 that extends radially inward from the perimeter surface 119.The radially-extending top surface 121 extends radially inward towards astep-shaped portion 123 (see FIG. 8). From this step-shaped portion 123,a cylindrical inner hub region 172 and peripheral rim 174 extend axially(i.e., parallel to central axis 54, when assembled into scrollcompressor assembly 10).

FIG. 8 shows the components of FIG. 7 fully assembled. The pilot ring160 securely holds the fixed scroll compressor body 110 in place withrespect to the movable scroll compressor body 112 and key coupling 140.The threaded bolts 168 attach the pilot ring 160 and crankcase 42. Ascan be seen from FIG. 8, each of the pair of first radially-outwardprojecting limit tabs 111 is positioned in its respective slot 162 ofthe pilot ring 160. As stated above, the slots 115 in the pair of firstradially-outward projecting limit tabs 111 are configured to receive thetwo axially-projecting first keys 144. In this manner, the pair of firstradially-outward projecting limit tabs 111 engage the side portion 193of the pilot ring slots 162 to prevent rotation of the fixed scrollcompressor body 110, while the key coupling first keys 144 engage a sideportion of the slot 115 to prevent rotations of the key coupling 140.Limit tabs 111 also provide additional (to limit tabs 113) axial limitstops.

Though not visible in the view of FIG. 8, each of the pair of secondradially-outward projecting limit tabs 113 (see FIG. 7) is nested in itsrespective notched section 166 of the pilot ring 160 to constrain axialmovement of the fixed scroll compressor body 110 thereby defining alimit to the available range of axial movement of the fixed scrollcompressor body 110. The pilot ring notched sections 166 are configuredto provide some clearance between the pilot ring 160 and the pair ofsecond radially-outward projecting limit tabs 113 to provide for axialrestraint between the fixed and movable scroll compressor bodies 110,112 during scroll compressor operation. However, the radially-outwardprojecting limit tabs 113 and notched sections 166 also keep the extentof axial movement of the fixed scroll compressor body 110 to within anacceptable range.

It should be noted that “limit tab” is used generically to refer toeither or both of the radially-outward projecting limit tabs 111, 113.Embodiments of the invention may include just one of the pairs of theradially-outward projecting limit tabs, or possibly just oneradially-outward projecting limit tab, and particular claims herein mayencompass these various alternative embodiments

As illustrated in FIG. 8, the crankcase 42 and pilot ring 160 designallow for the key coupling 140, and the fixed and movable scrollcompressor bodies 110, 112 to be of a diameter that is approximatelyequal to that of the crankcase 42 and pilot ring 160. As shown in FIG.1, the diameters of these components may abut or nearly abut the innersurface of the outer housing 12, and, as such, the diameters of thesecomponents are approximately equal to the inner diameter of the outerhousing 12. It is also evident that when the key coupling 140 is aslarge as the surrounding compressor outer housing 12 allows, this inturn provides more room inside the key coupling 140 for a larger thrustbearing which in turn allows a larger scroll set. This maximizes thescroll compressor 14 displacement available within a given diameterouter housing 12, and thus uses less material at less cost than inconventional scroll compressor designs.

It is contemplated that the embodiments of FIGS. 7 and 8 in which thefirst scroll compressor body 110 includes four radially-outwardprojecting limit tabs 111, 113, these limit tabs 111, 113 could provideradial restraint of the first scroll compressor body 110, as well asaxial and rotation restraint. For example, radially-outward projectinglimit tabs 113 could be configured to fit snugly with notched sections166 such that these limit tabs 113 sufficiently limit radial movement ofthe first scroll compressor body 110 along first lateral axis 146.Additionally, each of the radially-outward-projecting limit tabs 111could have a notched portion configured to abut the portion of the firstinner wall 169 adjacent the slots 162 of the pilot ring 160 to provideradial restraint along second lateral axis 154. While this approachcould potentially require maintaining a certain tolerance for the limittabs 111, 113 or the notched section 166 and slots 162, in theseinstances, there would be no need to precisely tolerance the entirefirst inner wall 169 of the pilot ring 160, as this particular featurewould not be needed to provide radial restraint of the first scrollcompressor body 110.

With reference to FIGS. 9-12, the upper side (e.g. the side opposite thescroll rib) of the fixed scroll 110 supports a floating seal 170 abovewhich is disposed the separator plate 30. In the embodiment shown, toaccommodate the floating seal 170, the upper side of the fixed scrollcompressor body 110 includes an annular and, more specifically, thecylindrical inner hub region 172, and the peripheral rim 174 spacedradially outward from the inner hub region 172. The inner hub region 172and the peripheral rim 174 are connected by a radially-extending discregion 176 of the base 116. As shown in FIG. 11, the underside of thefloating seal 170 has circular cutout adapted to accommodate the innerhub region 172 of the fixed scroll compressor body 110. Further, as canbe seen from FIGS. 9 and 10, the perimeter wall 173 of the floating sealis adapted to fit somewhat snugly inside the peripheral rim 174. In thismanner, the fixed scroll compressor body 110 centers and holds thefloating seal 170 with respect to the central axis 54.

In a particular embodiment of the invention, a central region of thefloating seal 170 includes a plurality of openings 175. In theembodiment shown, one of the plurality of openings 175 is centered onthe central axis 54. That central opening 177 is adapted to receive arod 181 which is affixed to the floating seal 170. As shown in FIGS. 9through 12, a ring valve 179 is assembled to the floating seal 170 suchthat the ring valve 179 covers the plurality of openings 175 in thefloating seal 170, except for the central opening 177 through which therod 181 is inserted. The rod 181 includes an upper flange 183 with aplurality of openings 185 therethrough, and a stem 187. As can be seenin FIG. 9, the separator plate 30 has a center hole 33. The upper flange183 of rod 181 is adapted to pass through the center hole 33, while thestem 187 is inserted through central opening 177. The ring valve 179slides up and down the rod 181 as needed to prevent back flow from ahigh-pressure chamber 180. With this arrangement, the combination of theseparator plate 30 and the fixed scroll compressor body 110 serve toseparate the high pressure chamber 180 from a lower pressure region 188within the outer housing 12. Rod 181 guides and limits the motion of thering valve 179. While the separator plate 30 is shown as engaging andconstrained radially within the cylindrical side wall region 32 of thetop end housing section 26, the separator plate 30 could alternativelybe cylindrically located and axially supported by some portion orcomponent of the scroll compressor 14.

In certain embodiments, when the floating seal 170 is installed in thespace between the inner hub region 172 and the peripheral rim 174, thespace beneath the floating seal 170 is pressurized by a vent hole (notshown) drilled through the fixed scroll compressor body 110 to chamber122 (shown in FIG. 2). This pushes the floating seal 170 up against theseparator plate 30 (shown in FIG. 9). A circular rib 182 presses againstthe underside of the separator plate 30 forming a seal betweenhigh-pressure discharge gas and low-pressure suction gas.

While the separator plate 30 could be a stamped steel component, itcould also be constructed as a cast and/or machined member (and may bemade from steel or aluminum) to provide the ability and structuralfeatures necessary to operate in proximity to the high-pressurerefrigerant gases output by the scroll compressor 14. By casting ormachining the separator plate 30 in this manner, heavy stamping of suchcomponents can be avoided.

During operation, the scroll compressor assembly 10 is operable toreceive low-pressure refrigerant at the housing inlet port 18 andcompress the refrigerant for delivery to the high-pressure chamber 180where it can be output through the housing outlet port 20. This allowsthe low-pressure refrigerant to flow across the electrical motorassembly 40 and thereby cool and carry away from the electrical motorassembly 40 heat which can be generated by operation of the motor.Low-pressure refrigerant can then pass longitudinally through theelectrical motor assembly 40, around and through void spaces thereintoward the scroll compressor 14. The low-pressure refrigerant fills thechamber 31 formed between the electrical motor assembly 40 and the outerhousing 12. From the chamber 31, the low-pressure refrigerant can passthrough the upper bearing member or crankcase 42 through the pluralityof spaces 244 that are defined by recesses around the circumference ofthe crankcase 42 in order to create gaps between the crankcase 42 andthe outer housing 12. The plurality of spaces 244 may be angularlyspaced relative to the circumference of the crankcase 42.

After passing through the plurality of spaces 244 in the crankcase 42,the low-pressure refrigerant then enters the intake area 124 between thefixed and movable scroll compressor bodies 110, 112. From the intakearea 124, the low-pressure refrigerant enters between the scroll ribs114, 118 on opposite sides (one intake on each side of the fixed scrollcompressor body 110) and is progressively compressed through chambers122 until the refrigerant reaches its maximum compressed state at thecompression outlet 126 from which it subsequently passes through thefloating seal 170 via the plurality of openings 175 and into thehigh-pressure chamber 180. From this high-pressure chamber 180,high-pressure compressed refrigerant then flows from the scrollcompressor assembly 10 through the housing outlet port 20.

FIGS. 13 and 14 illustrate an alternate embodiment of the invention.Instead of a crankcase 42 formed as a single piece, FIGS. 13 and 14 showan upper bearing member or crankcase 199 combined with a separate collarmember 198, which provides axial thrust support for the scrollcompressor 14. In a particular embodiment, the collar member 198 isassembled into the upper portion of the upper bearing member orcrankcase 199 along stepped annular interface 100. Having a separatecollar member 198 allows for a counterweight 230 to be assembled withinthe crankcase 199, which is attached to the pilot ring 160. This allowsfor a more compact assembly than described in the previous embodimentwhere the counterweight 130 was located outside of the crankcase 42.

As is evident from the exploded view of FIG. 13 and as stated above, thepilot ring 160 can be attached to the upper bearing member or crankcase199 via a plurality of threaded fasteners to the upper bearing member199 in the same manner that it was attached to crankcase 42 in theprevious embodiment. The flattened profile of the counterweight 230allows for it to be nested within an interior portion 201 of the upperbearing member 199 without interfering with the collar member 198, thekey coupling 140, or the movable scroll compressor body 112.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

For purposes of this disclosure, the term “coupled” means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or moveable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or the two componentsand any additional member being attached to one another. Such adjoiningmay be permanent in nature or alternatively be removable or releasablein nature.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the embodiments (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential.

Preferred embodiments are described herein, including the best modeknown to the inventors for carrying out the invention. Variations ofthose preferred embodiments may become apparent to those of ordinaryskill in the art upon reading the foregoing description. The inventorsexpect skilled artisans to employ such variations as appropriate, andthe inventors intend for the invention to be practiced otherwise than asspecifically described herein. Accordingly, this disclosure includes allmodifications and equivalents of the subject matter recited in theclaims appended hereto as permitted by applicable law. Moreover, anycombination of the above-described elements in all possible variationsthereof is encompassed by the disclosure unless otherwise indicatedherein or otherwise clearly contradicted by context.

What is claimed is:
 1. A scroll compressor including a load transferapparatus, the compressor including a rotating shaft and a stationarylower bearing member, the load transfer apparatus comprising: a centralcylindrical hub defined by the stationary lower bearing member, whereinthe central hub defines an opening; a cylindrical bearing configured toseat in the opening, with the cylindrical bearing further configured toreceive one end of the shaft; and a thrust washer disposed in theopening of the central hub and captured axially within the lower bearingmember by the cylindrical bearing, wherein an axial load along thecenterline of the shaft transmits to the stationary lower bearing memberthrough the thrust washer.
 2. The scroll compressor including a loadtransfer apparatus of claim 1, wherein the thrust washer is fixedaxially and rotationally in the opening without a fastener or anadhesive.
 3. The scroll compressor including a load transfer apparatusof claim 1, wherein the thrust washer includes a smooth circumference.4. The scroll compressor including a load transfer apparatus of claim 1,wherein the thrust washer is metal.
 5. The scroll compressor including aload transfer apparatus of claim 1, wherein the cylindrical bearing iscomposed of a matrix of metal and a polymeric layer.
 6. The scrollcompressor including a load transfer apparatus of claim 5, wherein thecylindrical bearing is lubricated by oil transferring through an orificedefined in the shaft.
 7. The scroll compressor including a load transferapparatus of claim 1, further comprising: scroll compressor bodiesdisposed in a housing, the scroll bodies including a first scroll bodyand a second scroll body, the first and second scroll bodies havingrespective bases and respective scroll ribs that project from therespective bases, wherein the scroll ribs mutually engage, the secondscroll body being movable relative to the first scroll body forcompressing fluid; and a pilot ring that engages a perimeter surface ofthe first scroll body to limit movement of the first scroll body in theradial direction, the first scroll body having a firstradially-outward-projecting limit tab being configured to limit movementof the first scroll body in at least one of the axial and rotationaldirections.
 8. The scroll compressor including a load transfer apparatusof claim 7, wherein the first scroll body includes the firstradially-outward-projecting limit tab and a secondradially-outward-projecting limit tab, the first and secondradially-outward-projecting limit tabs spaced approximately 180 degreesapart, and wherein the pilot ring has two notches adapted to receive thefirst and second radially-outward-projecting limit tabs.
 9. The scrollcompressor including a load transfer apparatus of claim 1, wherein thepilot ring is formed separately from a crankcase, the pilot ring beingattached to the crankcase via a plurality of posts extending axiallytherebetween, the first and second scroll bodies being disposed withinthe attached pilot ring and crankcase, and further comprising a keycoupling that acts upon the second scroll body, the key coupling beingdisposed within the attached pilot ring and crankcase, and extendinginto spaces between adjacent posts, and whereby the spaces allow thepilot ring, crankcase, and key coupling to have outer diameters that areapproximately equal to the inner diameter of the housing.
 10. A methodfor transferring axial loading from a rotating shaft in a scrollcompressor to a stationary lower bearing member of the scrollcompressor, with the rotating shaft having an axial load including themass of the shaft, a motor rotor, and counterweights of the scrollcompressor plus electrical induced load caused by misalignment of themotor rotor and a motor stator, the method comprising: depositing athrust washer at the bottom of an opening in a central cylindrical hubdefined by the stationary lower bearing member; inserting a cylindricalbearing into the opening in the central cylindrical hub; pressing thecylindrical bearing into the opening axially until the bearing capturesthe thrust washer into position axially in the opening; and inserting anend of the shaft into the cylindrical bearing in the opening defined inthe central cylindrical hub, wherein the axial load on the shaft alongthe centerline of the shaft is transmitted to the stationary lowerbearing member through the thrust washer.
 11. The method fortransferring axial loading from a rotating shaft in a scroll compressorto a stationary lower bearing member the scroll compressor of claim 10wherein the thrust washer is composed of one of a metal and a matrix ofmetal and a polymeric layer.
 12. The method for transferring axialloading from a rotating shaft in a scroll compressor to a stationarylower bearing member the scroll compressor of claim 10 wherein thethrust washer is configured with a smooth circumference.
 13. The methodfor transferring axial loading from a rotating shaft in a scrollcompressor to a stationary lower bearing member the scroll compressor ofclaim 10, further comprising lubricating the cylindrical bearing withoil through an orifice in the shaft.